This invention relates to gravity fed shelving for product conveyance, such as at the retail level and, more particularly, to improved rollers and tracks therefor.
Roller-type gravity fed shelving is typified by the roller-type commodity stand of U.S. Pat. No. 6,089,385, and the Conveyor of U.S. Pat. No. 5,048,661. Additionally, there are also the xe2x80x9cVolume Masterxe2x80x9d (Trademark) gravity flow tracks made by Anthony Manufacturing Company, Inc., of San Fernando, Calif. Finally, the assignee of the present application also has long made its NylaRol(copyright) gravity flow shelving. Particularly, rollers transversely mounted at spaced locations along one or more track members, and with their uppermost height stationed at a point above the tracks, are used to roll-convey product along the track. In a gravity-fed alignment situation, the rear of the track is higher than the front or dispensing end, and product is fed by gravity and rolls to the frontmost available position along the track.
Because of the various products needing conveyance, e.g. half gallon milk containers on the one hand versus soft drink cans and cartons of half and half cream on the other hand, product widths vary greatly. When used in retail sales settings, e.g. convenient stores, it is imperative that such gravity fed roller tracks operate smoothly, continuously feed the product to the front without a product xe2x80x9changupxe2x80x9d on any portion along the track, and can be easily installed and cleaned. However, various problems are found with the prior art gravity fed roller products. For example, separate track members are often required for each unit; the units are difficult to clean when there has been spillage (e.g., milk leaking from a container); the roller hubs often extend beyond the outer limits of the exterior track walls, thereby causing restriction to roller spin in many cases; the use of large-diameter rollers inherently creates a larger than desirable, center-to-center distances between roller axes; neither the rollers nor the tracks can be removed from the angled shelf without disassembly, i.e. creating expensive and time consuming cleanings and adjustments; and different width products require different sized rollers and tracks. Regarding the latter, when the prior larger-diameter rollers are utilized, smaller product containers, e.g. quart containers and square half gallon containers, often ride rough, and even hangup during gravity feeding, due to the larger center-to-center distance between rollers.
The z-tray of the present invention is easily formed from a stamped flat metal sheet, and then formed up to create the unique z-shape, whereby the hubs of the unit-length mini rollers are rotatably supported in the side walls of the z-tray, while the upper (or xe2x80x9crolling engagementxe2x80x9d) surface of each roller is maintained at a height above the supporting side walls of the z-tray. Once formed, the z-tray is a one piece, completely removable and easily cleanable rigid conveyor roller track, without any separate track members being required. The present z-tray design permits a minimum of clearance between adjacent product conveyance lanes. Since the roller hubs do not extend beyond the outside limits of the exterior vertical walls of a given z-tray, there is no chance for roller spin restriction, as is common in the prior art. The small center-to-center dimensions available through the use of the present small diameter unit rollers, permits successful transport of very small product packages, i.e., less than 3xe2x80x3 in depth.
The glass filled injectable plastic material preferably used for molding the present mini rollers enable each roller to be molded without distortion, and the glass fill assists in increasing the strength and hardness of each roller. To create optimal rolling ability, and thereby reduce friction, a preferred axial diameter-to-roller diameter ratio is utilized for the present mini roller part.
The present invention overcomes the problems in the prior art by providing a specially configured xe2x80x9cz-trayxe2x80x9d for use with small-diameter rollers, preferably formed as injection molded and glass-filled members. To accommodate larger product width, as compared to small product width, the same length, small-diameter roller of the present invention can be utilized, but simply with a z-tray that has been formed with wider outside retaining walls, still leaving the rollers high. That is, whether a given z-tray is for a large product or a small product, its roller support structure is formed to retain the same size mini roller, and the outside retaining walls are then closer or farther apart depending on the conveyed product""s width. Further, larger diameter prior art-style rollers, such as the standard aluminum tube with nylon hub-type roller commonly used, can be retrofitted into the present invention""s z-type tray to create an improved gravity fed roller track having lift out and easy cleaning capability.